Spark-plug



O. M. LEICH.

SPARK PLUG.

APPUCATION FILED Nov. 6. 1919.

1,375,85 1. Patented 11.126, 1921.

UNITED s'riirrsl PATENT OFFICE.

OSCAR M. LEICH, 0F GENOA., ILLINOIS, ASSIGNOR T0 LEICH ELECTRIC COMPANY, 0F GENOA, ILLINIS, A. CORPRATION OF ILLINOIS.

SPARK-PL.

Specification of Letters Patent.

Patented Apr. 26. 1921.

Application tiled. November 6, 1919. Serial No. 336,15?.

To all whom 'it 'may concern.'

Be it known that I, 'OSCAR M. lauren, a citizen of the United States, residin at Genoa, in the county of De Kalb and tate of illinois, have invented a certain new and useful Improvement in Spark-Plugs, of which the following is a full, clear, concise, and exact description7 reference being had tothe accompanying drawings, forming a part of this specification.

My invention relates to spark plugs and more particularly to a spark plug which is adapted to be used to ignite the charge of a gasolene engine. Spark plugs of this nature must be of substantial construction, positive in operation and must be so constructed' as to insure sparking at all times under the voltages ot the ordinary batteries used in connection with engines of this kind.

It is an object of the invention to provide a spark plug with means for aiding the discharge ofthe main spark across the spark 'in the drawinnfs.v In the drawings li have disclosed one Form of my invention which form is the best known to me at the present time. However, it is to be understood that4 by this specification and the accompan ing drawings l do not intend to limit mq se to the specific construction disclosed. he descriptive words used herein are used .in a merely descriptive sense and not in a limiting sense.- rFhe real nature and scope of the invention disclosed is to be determined from the claims, appended to this specication.

The same reference characters have been used to designate the same parts throughout the several views of the drawings wherein- Figure 1 is a vertical section taken through my improved spark plug;

Fig. 2 is a horizontal section taken on line 2--2 of Fig. 15

Fig. 3 is a top view of the plug shown in Fig. 1.

ln the drawings the reference numeral 10 desi ates the bod or shell member oi the spar Yplug which ody member is provided With the -usual wrench engaging surface. rlhis body member is also provided with a threaded portion 11 which is adapted to enga e the threaded opening in the cylinder of t e en ine. 'lhe body member here shown is a so provided with a shoulder 12 which engages the gasketwhich is inserted between the engine and plugs of this kind. Of course, it will be understood that if plugs are formed with the standard pipe thread that the shoulder will not be present.

Contained within the body or shell member 10l is the' insulating base 13 which is shaped approximately as shown in the drawings and has an enlarged shoulder portion 1t which rests upon the shoulder 15 within the body member 10. A gasket 16 is inserted between the body member 10 and the shoulder 14 as shown in Fig. 1. A second gasket 17 is placed above the shoulder 14 and this gasket is adapted to be engaged by the nut 18 which has exterior threads which are adapted to engage interior threads near the upperA end of the body member 10. The nut 18 is provided with the usual wrench engaging surface 19 whereby the nut may be removed from the body member 10 in order that the orcelain may be removed or replaced. *xtending centrally through the insulating base 13 is the central electrode 20. This electrode is provided Iwith an enlarged screw threaded portion 21 which tits into a recess 22 in the top of the insulating base 13. I also prefer toprotect the top of the insulating base by means of a metallic cap 23 shaped as shown in Fig. 1. The plate 23 is in electrical contact with the screw threaded portion 21 of the electrode 20. Positioned on the screw threaded portion 21 is the usual terminal engaging nut 2li which is so shaped thatl terminals of di'erent kinds may be used. A terminal having a flat connecting element may be inserted between the nut 24 and the plate 23. The terminal having a fork shaped connectinor element may be engaged around the smaller portion of the nut. A terminal having a cup shaped engaging element may be slipped over the nut in the usual manner. v

ln the lower end of the insulating base 13 is provided a recess 25 and the lower end of the main electrode 20 extends through this recess and slightly beyond the end of the insulating base as shown in Fig. 1. T he insulating base is provided as shown in F1g.

1 with an enlarged extremity 26 preferably shaped as shown. Surrounding this enlarged extremit is a metallic cap 27 whlch is provided wit a star shaped opening 28 through which the end of the electrode extends. The edges of this opening are provided with projecting portions 29 which extend inwardly or toward the main electrode 20 but are spaced therefrom so that there will be no electrical connection between the metallic cap and the electrode 20. The metallic cap is bent around the enlarged extremity 26 as shownin Fig. 1 so that no additional means is necessary.

The second main electrode 30 is shaped as shown in Fig. 1 and is securely fastened to the metallic body member 10. The electrodes 20 and 30 form between them the usual spark gap 31. This gap will be adjusted to suit the conditions under which the spark plug is to be used.

The operation of my spark plug is as follows: When current passes through the main electrode 20 it will jump across the gap 31 to the electrode 30. The resistance,

at this gap is very great due to the compressed condition of the air or gas around the end of the plug at the time the discharge or spark is to occur. Because of this great V'resistance there is considerable lag in the spark when therspark plugs of ordinary construction are used. My device eliminates this lag in the following manner. The metallic cap 27 is carried by the insulating base 13 and has no electrical connection with any portion of the spark plug. When the main discharge or spark occurs between the electrodes 20 and 30 the metallic cap 27 becomes charged with electricity due tothe fact that it is in close proximity to the parts of the plug which form part of the circuit. The metallic cap 27 acts as an electric condenser and due to this condenser or capacity eect a discharge takes place between the metallic cap and the central electrode 20 in advance ofthe main spark or discharge. The metallic cap 27 may properly be called an auxiliaryelectrode. The discharge from this auxiliary electrode to the main electrode 20 although small and hardly visible with the naked eye will produce ionization of the gap or air around the electrode 20 thereby increasing the number of ions in the-main gap. Due to thepresence of these ions a ischarge of the main gap will be eiected at of given length. This is due to the fact that when the normal break down voltage is Vreached the discharge does not take lace immediately and the' voltage will elther have to be maintained for'a time or rise above the normal discharge value to the extent at which the dischargeactually takes place. This phenomenom 1s called the lag of the discharge. My improved spark plug provides means for the ionization of the gas in the main spark gap causin the current to discharge at a lower vo tage and thereby almost overcoming` the lag of the discharge. This will allow for a longer period of' discharge for each current wave thereby supplying more energy or heat to each discharge. My improved plug provides better ignition and therefore causes the engine to run better and cause the plugs to remain free from carbon and oil deposits.

The auxiliary electrode 27 is substantial in construction and cannot be readily displaced. It may be easily cleaned and has no rough or protruding corners. The rojectionsl 25 are spaced only a slight distance away from the main electrode 20. If the free end of the main electrode 20 is bent in any direction it strikes one or more of the projections 29 before it reaches the elastic limit of the metal of which the electrode is made. The electrode will therefore spring back to its normal or central position. The auxiliary electrode therefore prevents any accidental or wilful bending of the exposed end of the electrode 20. AThe electrode and cap therefore remain in their predetermined fixed relation and the space between the electrode and the projections 29 remains constant. The function and operation of the cap therefore remain unchanged. The cap 27 completely incloses and protects the end of the insulating base 13. If the insulating base and its electrode are removed and replaced there will be no chance for the main and auxiliary electrodes to get out of alinement. This is a decided advantage and improvement over the s ark plug shown in my former application erial No. 283,566, filed Mar. 19, 1919. The cap 27 being rigid cannot be bent as ma occur with the auxiliary electrode 12 o the Radtke Patent No.`

base and an auxiliary electrode carried by said insulating base adjacent said main electrode and inclosin the end of said base, said ltwo main electr es being in juxtaposition electrode carried by said insulating base'and spaced from said lirst electrode to provide a spark ap between them, and means carried by saiginsulating base for ionizing the gas and air adjacent said spark ga and adapted to prevent undue bending of tlie end of said second electrode.

3. A spark plu of the character described comprising a body member and an insulating base secured therein, a main electrode carried by said body member, a second main electrode carried by said insulating base and spaced from said first electrode to provide a spark' gap between them, said two main electrodes being in juxta-position whereby the main spark passes directly between them, and means carried by said insulating base for preventing bending of said second electrode.

' 4. A spark plug of the character described comprising a metallic body member and an insulating member, cooperating main electrodes carried respectively by said body member and said insulating base, and an auxiliary electrode carried by said insulating base for ioniz the gas or air adjacent the ends of said mam electrodes, said auxiliary electrode substantially inclosing the end of i said insulating base to thereby hold it firmly member andy said insulating base, said two main electrodes being in juXta-positi'on whereby the main spark passes directly between them, and an auxiliary electrode'carried by` said insulating base for reventing bendin of the free end of one o said main electro es.

6. A spark plug comprising an insulating base having a rece in one of its ends, an electrode extending throngh'said insulating base and havingits free end projecting into saiderecess, a metallic cap secured to the end of said insulating base and spaced from the free end of said main electrode s0 aS to pre- :sel

vent bending of said end in said recess beyond its elastic limit.

7. A spark plug of the character described comprising a metallic body member and an insulating base secured Within said body member, coperatin main electrodes carried respectively by sai body member and said ating base, and means adjacent said electrode for ionizing the gas or air between said electrodes, said means also preventing bending of one of said electrodes.

8./A spark plug comprising a metallic I mg of said secon main electrode beyond its elastic limit.

In witne whereof; I hereunto subscribe my name this 4th day of lNovember, A. D.

OSCAR M. LEICH. 

